Manufacture of indigo-white preparations suitable for fermentation-vats.



UNITED sTAT s PATENT OFFICE.

ALBRECHT SCHMIDT, OF HOOHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO FARBWERKEVORM. MEISTER LUCIUS & BRUNING, OF HOCHST-ON-THE-MAIN, GERMANY, A COR-PORATION OF GERMANY.

MANUFACTURE OF INDIGO-WHITE PREPARATIONS SUITABLE FOR FEBMEN'IATION-VATS.

Specification of Letters Patent.

Application filed March 22, 1905. Serial No. 261,447.

Patented Dec. 8, 1908.

To all whom it may concern:

Be it known that I, ALBRECHT SCHMIDT, Ph. D., chemist, a citizen of theEmpire of German and residing at Htichst-on-the- Main, Germany, haveinvented certain new and useful Improvements in the Manufacture ofIndigo-White Preparations Suitable for Vats, EspeciallyFermentation-vats, of which the following is a specification.

A considerable part of indi .0 is used for the fermentation-vat, esecially in Eastern countries. The chemica vats require the indigo to bein a fine state of sub-division and capable of being readily made into apaste, a condition all the more essential for the fermentation-vat. Thereason why synthetic indigo has hitherto not been able to supplantnatural indigo is that the latter is readily soluble in thefermentation-vat, yielding excellent vats, whereas the conversion ofsynthetic indigo into a soluble vat meets with greater difiiculties.This disadvantage of the synthetic indigo is" due to the physicalcondition of the products in question, which may be explained by thevarious methods of their preparation. Natural indigo is isolated at itsplace of production as a fine amorphous powder from the lucosid ofstrongly diluted indigo-white. ts partioles are so fine as to resistonly slightly the reducing action of agents in the vat and thus arereadily dissolved.

Synthetic indigo is obtained from comparatively very concentratedsolutions of indoxyl by oxidation and condensation; under thesecircumstances synthetic indigo is produced in crystalline form. As aconsequence of its physical structure, the synthetic indigo greatlyresists the gentle reducing agents of the vat, so that the artificialproduct dissolves only insufiiciently in the difierentfermentation-vats. From a commercial point an essential difference hasto be made between natural and synthetic indigo. As

soon as this difference was recognized by the producers, efiorts weremade to bring the synthetic indigo into such a form as to permit itsbeing used in the fermentation-vat.

It has been tried to obtain synthetic indigo in a finely divided stateby grinding indigo powder in the disintegrator, without, however,attaining the desired state of fine subdivision of natural indigo. Thepastes prepared by the consumer in grinding indigo powder in a moistcondition did not come near to the reducibility of natural indi o. Norwas the object attained by means of t e known process of treating indigowith sulfuric acid. Further experiments were made to treat indigo cakessimilar to alizarin cakes, with starch, dextrin etc. These indigo-lumps,however, could not supersede the natural indigo in thefermentation-vats. Another method to obtain a suitable product was tomix indigo pastes with ferments and alkalies, yet with no better result.None of these methods succeeded in giving to the synthetic indigo such aform as to permit a competition with the natural indigo.

The best preparation hitherto obtained is that in form of a paste of20%. It has supplanted natural indigo in all chemical vats,

but for the fermentation-vat, especiallyin the East, it is not that whatis wanted. Apart from the little reducibility, the pasty form is ratherinconvenient for transport and little suitable for the small. consumerof the East, for, as soon as the packages are opened the paste soonbecomes dry and very difficult to reduce afterwards. Applicant has triedanother way to overcome these difiiculties and.

succeeded in obtaining a highly concentrated indigo-preparation moresuited for the fermentation-vat than natural indigo. This processconsists in mixing indigo-white with molasses, syrup and similar bodies.The difiiculties to overcome were to obtain a vat preparation having thefollowing characteristics:

1. The vat or indigo-white composition had to be highly concentrated forreasons of transport and at the same time capable of being made into apaste.

2. Stability towards the oxidizing action of the air, ermitting even theuse of not quite air-tig t barrels.

3. The-composition should not be infiu enced by the warm atmosphere ofthe East,

' even after the barrel or like packing has been opened, that is to say,the preparation must .at any time be capable'of being made into a pastecontaining t e indigo in form of indigowhite ca able of reaction.

It is 0 car that from the outset there was little ho e to find such apreparation answering all t ese requirements. In fact, the first use fora long time, even before synthetic -ingt indigo, possessslightlyantiseptic'pro erties' indigo was known, but a concentratedindigowhite preparation has never been known on the market. Otherattempts were madev to give to indigo-whitea concentrated, stable form,by producing formaldehyde-indigowhite, carbonic acid ester-indigo-white,acetic acid ester-indigo-white etc., yet all these methods were by fartoo expensive and useless for the fermentation-vat, as these compoundshad first to undergo an isolating process. I

Now, while preparing a fermentatican-vat with indigo-white instead ofindigo, in pres-- ence of molasses as organic nutrient, indigowhitepress cakes stirred with water were mixed and this mixture was added tothe fermentation-vat. It was observed that the dried-up parts, insteadof becoming blue by the oxidation of the air, were left intact. Theaddition of molasses evidently had a peculiarly preserving influenceonthe indigo white, as was proved afterwards by further experiments. Anexperiment based on this observation for obtaining a commercial productby mixing molasses and indigo-white met with no successin anotherdirection, for it is shown, that mixtures of indigo with organic bodies,such as starch, dextrin etc. soon become moldy. Compare British patentNo. 3108 04;,lines 6-13. The addition of alkali'hydrateor lime as givenin this patent is only of momentary, advantage, as by alloweindigo-white roduct to stand,.the alkali disa pears an the mass beginsto mold and erment. -By further tests it was found that b impregnatingindigo-white sufliciently wit concentrated molasess, products maybeobtained which are not only stable towards the influence of the air, but

also towards mold and fermentation. .The' reasonfor this was found inthe-fact that technical indigo-white, brominated indigowhite,tolyl-indigo white etc., contrary to and that molasses, especially whenighly concentrated, have a preservative action as a consequence oftheir-containing sugar and considerable proportions of salts. It is thustam'pa'stes containing 30, 40, and more er cent. of indigps-white, whichmay be simply packed in'cas where they remain intact, even when parts ofthe conpossible to o indigo-white,

- molasses.

tents have been used. It is remarkable that these products may bereadily made into pastes without becoming dry, which is due to the largeroportion of hygroscopic salts and-liquefiab e substances containedtherein. The contents of Water of the products may even be reduced sofar as to obtain no longer pastes but solid bodies, such as lumps,powder etc. and yet these products are still capable of being made intopastes without losing their favorable propertles.

Stable indigo-white preparations may be obtained in difl'erentways,according to the I degree. of consistency of the product desired. Forinstance, indigo-white ress-cakes may be directly mixed with mo asses orsyrup, part of the water being distilled ofi in a suitable apparatus,such as in a vacuum, until the desired product is obtained, either as apaste,

or in a semi-solid or solid form. Or the moist lpfiessed hydraulically,may be mixed in the eading machine with molasses, until a handy paste isobtained, oragain,

indigo-white ress cakes are washed out with molasses an the roduct thusobtained is stirred alone or with a further quantity of The proportionsof indigo-white and molasses vary according to the product desired;though, in general, it is not of advantage to allow the quantity ofwater in the molasses to be too great, as in case of too strong adilution, the roduct is more liable to become moldy. T e new productsform concentrated, stable, indigo-white pre ara: tions which are solublein dilute so al e with a yellow-green solution from whic when exposed tothe air, blue flakes se 31- rate, partly soluble in water, the insolu lepart being soluble in soda-lye, while the part soluble in water showsthe known reaction of saccharides.

(containing about 75 per cent. of dry indigo) .obtained by means ofzinc, bisulfite, h drosulfite. or electrolysis and hydraulically glossedat about 200 atmos heres in the eading machine, are stirre stance, 700or about 400parts of thickly liquid molasses or any sugar syrup, canesugar, invert sugar, maltose, glucose, maltose or other saccharinesubstance, further dehydrated if necessary. The pasty product may beused at once. Example II. The rocess isthe same as in ,Example I, onlyfor t e hydraulically pressed indigo-white, indigo-white paste isused,-by mixing 280 kil. of press-cakes (=80 parts of indigo-white)with, for instance, 100, 80 or 50 parts of molassesor sugar syrup, canesugar, invert sugar, ucose, or other saccharine substance, suc forinstance, as milk sugar, preferably in presence of other sugars readilysoluble in water, from which about 100-170 parts of water are distilledoff in a vacuum, so that after evaporating, a pasty with, for in or iffurther distilled, a solid obtained.

The process described for digo-White from indigo may also be applied toother indigo-white derivatives (substitution products), such, forinstance, as indigowhite from meth l-indigo, (tolyl-indigo), especiallyortho-tolg l-indigo or as halogenproduct is finally indigo-whites, forinstance, brominated', di-

brominated and chlorinated indigo.

Having now described my invention, what I claim is:

1. The process herein described of making concentrated, stable, indigowhite preparations especially suitedfor fermentation-vats, whichconsists in incorporating indigo-whites with saccharine substances. 2.As new-products, concentrated, stable,

obtaining in-f which, when exposed to the air, blue flakes,will-separate, artly soluble in water, Whereby the insolu 1e art issoluble in soda-lye, and the part so uble in water shows the knownreaction of saccharide's.

In testimony that I claim the foregoing as my invention, I have signedmy name .in

presence of two subscribing Witnesses.

; ALBRECHT SCHMIDT.

Witnesses JEAN GRUND,

CA L GRUND.

